Saw assembly

ABSTRACT

A saw assembly for a grip-harvester has a saw chain running around a bar and a chain sprocket; a bar holder pivotably journalled on the saw assembly stand; a saw motor driving the chain sprocket; and a device for feeding a bar out and in. The feeding-out and feeding-in device preferably is a hydraulic cylinder mounted on the stand and having a piston rod. The movements of the piston rod are transmitted to the pivotable bar holder by means of a pivotably journalled first toothed wheel which is joined to the bar holder and has a toothed wheel rim cooperating with the piston rod which is in the form of a rack. The saw assembly is also provided with a device for sensing and recording the angular position of the saw bar in relation to an initial position, which device has a smaller second toothed wheel in engagement with the first larger toothed wheel of the feeding-out and feeding-in device, and also at least one sensor which senses a tooth gap or a tooth on the second toothed wheel.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national phase of international applicationNo. PCT/SE98/00961 filed May 22, 1998.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a saw assembly for a grip-harvester,comprising a stand; a bar; a saw chain running around the bar and achain sprocket; a bar holder pivotably journalled on the stand; a sawmotor driving the chain sprocket; and a feeding-out and feeding-indevice for feeding the bar out and in to perform a sawing operation,said feeding-out and feeding-in device comprising a hydraulic cylindermounted on the stand and having a piston rod, and connection means totransmit the movements of the piston rod to the pivotable bar holder.

In previously used saw assemblies of the type described in theintroduction the mechanical connection for transmitting the movement ofthe hydraulic cylinder to the bar holder is constructed of movable partsand these can therefore be subjected to external influence causingdamage to the connection, or snow and ice may collect around theconnection thus deteriorating or completely destroying its function. Incertain cases special guides are also required for the piston rod, totake up the radial forces this is subjected to during said transmissionof movement. The known saw assemblies have no efficient device forsensing and recording the angular position and direction of movement ofthe saw bar in relation to its home position. Without such efficientdevice it is impossible to arrange an efficient marking system tocolour-mark a sawn cut surface, for instance, in conjunction with theactual sawing operation.

The object of the present invention is to considerably reduce theproblems mentioned above and provide a simplified saw assembly whichlacks movable parts between the piston rod and the element which iscaused to rotate and comprises the bar holder, and which saw assemblycan be provided with an efficient device for sensing and recordingangular position and direction of movement of the saw bar so it is alsopossible to make use of an efficient marking system. This is enabledwhile still retaining the dimensions of the saw assembly, or even withreduced dimensions.

The saw assembly according to the invention is characterized in thatsaid connection means comprises a toothed wheel pivotably journalled inthe stand, which toothed wheel is coaxially, rigidly joined to the barholder and is provided with a toothed wheel rim or a sector of a toothedwheel rim situated on a level with and facing the piston rod, in thatthe piston rod is in the form of a rack with teeth facing the toothedwheel and in engagement with the teeth on the rim or the rim sector, inthat the saw assembly comprises a device for sensing and recording theangular position of the saw bar in relation to an initial position,which device comprises a toothed wheel in toothed engagement with thetoothed wheel of the feeding-out and feeding-in device and is smallerthan the toothed wheel so that a gear ratio >1 is obtained between thelarger toothed wheel and the smaller toothed wheel, and also a sensorwhich, in an initial position of the saw bar, is situated immediatelyopposite a gap between two teeth or immediately opposite a tooth in saidsmaller toothed wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail with reference to thedrawings.

FIG. 1 shows schematically from above parts of a saw bar, partially insection.

FIG. 2 shows the saw assembly according to FIG. 1 more in section.

FIG. 3 shows the saw assembly according to FIG. 1 with its saw bar infed-out position.

FIG. 4 shows the saw assembly according to FIG. 1 and illustrates itsfeeding-out and feeding-in device for the saw bar, and also a built-inlubricating oil pump.

FIG. 5 is a view of the saw assembly according to FIG. 1 seen from oneend, partially in section.

FIGS. 6 and 7 show a top view and a side view, respectively, of atoothed wheel and bearing means of the saw assembly according to FIG. 1.

FIGS. 8 and 9 show top and side views, respectively, of a saw motorincluded in the saw assembly according to FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show schematically parts of a saw assembly mounted in aso-called saw box, which is intended for inclusion in a grip-harvester.The saw assembly comprises a stand 1, a bar holder 2 and a bar 3 mountedon the bar holder 2 with the aid of suitable bar attachments andassembly devices so that a displaceable unit is formed including saidbar 3. A saw chain 4 runs around the bar 3 and a chain sprocket 5 (seeFIG. 5), which is driven by a saw motor 6 (see FIG. 8) via a drive shaft7 (see FIG. 5) which also carries a chain guard 8. The saw motor 6 isrigidly secured inside the stand 1. The bar holder 2 is pivotablyjournalled in relation to the stand 1 by bearing means 9 (see FIG. 5),to be turned in controlled manner about an axis 10 coinciding with thecentral axis of the drive shaft 7 of the saw motor 6.

Said unit is thus mounted on the bar holder 2 so that the bar 3 can bedisplaced in relation to this in a direction corresponding to thelongitudinal centre line 11 of the bar 3 and which is perpendicular tosaid axis of pivot 10. A first hydraulic piston cylinder (not shown) isarranged in one of said bar attachments to be activated by a hydrauliccircuit system of the saw assembly via a directional valve and aconnection comprising an outer pipe 12 (see FIG. 4) for displacement ofthe unit in relation to the bar holder 2 so that, during operation ofthe saw assembly, the bar 3 in the unit automatically keeps the sawchain 4 taut. A second hydraulic piston cylinder (not shown) is arrangedin one of the bar attachments to act in parallel with the axis of pivot10 in order to press against the bar holder 2 in a controlled manner toflexibly secure the movable unit to the bar holder 2. The other pistoncylinder is also affected by the pressure in said hydraulic circuitsystem via said outer pipe 12.

The saw assembly comprises a device 14 for controlled feeding of the bar3 out and in by turning the bar holder 2 about the axis of pivot 10. Thestand comprises an oblong side part 15, situated tangentially inrelation to the central stand part 16, in which the saw motor 6 issituated. The feeding-out and feeding-in device 14 comprises a hydrauliccylinder 17 which is coaxially rigidly mounted on one end of the oblongstand side part 15. The piston cylinder 18 of the hydraulic cylinder issituated behind the bar 3, seen in its direction of movement, andparallel to the bar 3 when this is in its initial position prior to asawing operation. The piston rod 19 of the hydraulic cylinder issituated in the stand side part 15 and is shaped as a rack, its sidefacing the axis of pivot 10 being provided with a section having aplurality of teeth 20--twelve teeth in the embodiment shown. Hydraulicfluid is supplied to and removed from the two pressure chambers 21, 22(see FIG. 4) of the piston cylinder 18 via pipes 23, 24 connected to thehydraulic circuit system of the saw assembly via a directional valve(not shown), which pressure chambers 21, 22 are defined by a piston 25carried by the rack 19. The feeding-out and feeding-in device 14 alsocomprises a toothed wheel 26 with a rim 27, with which the rack 19 ofthe hydraulic cylinder is in engagement. The toothed wheel 26 has acylindrical body 28 (see FIG. 5) and is rigidly joined to the bar holder2 to form a unit therewith which can be turned about said axis of pivot10. The rigid connection is achieved by means of axial bolts 29 (seeFIG. 5) which are screwed into the lower part of the toothed wheel body28 and which extend through borings in the peripheral part of the barholder 2. Said bearing means 9, which enables turning of the bar holder2, is situated within the area, i.e. within the axial extension of thetoothed wheel 26. The bearing means 9 consists of a ball bearing with anouter bearing ring 30 formed by the radially inner part of the toothedwheel 26, and an inner bearing ring 31 with which the saw motor 6 isjoined to form a rigid unit, i.e. so that the inner bearing ring 31cannot be turned about the axis of pivot 10. Between them the bearingrings 30, 31 carry balls 32 in two tracks, the ball races being out ofround so that the ball bearing functions as a four-point bearing. Theinner surface 33 of the inner bearing ring 31 is cylindrical and formsan assembly support for the corresponding externally cylindrical surface64 of a longitudinally extending assembly shaft 65 of the saw motor 6(see FIG. 8), the saw motor having an inner radial flange 66, the lowerside 67 of which rests on the radial upper surface 35 of the innerbearing ring 31, and the peripheral axial surface 68 of which cooperateswith an inner opposite axial surface 36 of the upper part 37 of thetoothed wheel body 28.

The saw assembly also comprises a lubricating oil pump 38 (see FIG. 4),arranged to provide the saw chain 4 with lubricating oil when the bar 3is fed out. In the embodiment shown the lubricating oil pump is builtinto the hydraulic cylinder 17 itself in order to form an integratedunit therewith and be served thereby. The lubricating oil pump 38comprises a central, longitudinally extending pump chamber 39 (see FIG.4) inside the rack 19 in the part facing the piston cylinder 18, andalso a central pipe 40 extending through the piston cylinder 18 and intosaid pump chamber 39 so that one end is always situated in the pumpchamber 39. The pump chamber 39 is closed off from the pressure chamber21 of the hydraulic cylinder 17 by means of suitable sealing elements 41comprising a sealing ring 42. The hydraulic cylinder 17 is closed at theend facing away from the piston rod 19 by means of a valve housing 43 inwhich said central pipe 40 extends for rigid assembly therein. The pumpchamber 39 is supplied with lubricating oil from a lubricating oil tank44 (see FIG. 4) via an outer pipe 45, a first channel 46 in the valvehousing 43 and the central pipe 40. Lubricating oil is pumped out fromthe pump chamber 39 via the central pipe 40, a second channel 47 in thevalve housing 43 and an outer pipe 48 connected to an inlet 49 in thecover 50 of the saw motor. The first and second channels 46, 47 in thevalve housing 43 are provided with non-return valves 51, 52,respectively. It will be understood that lubricant is pumped out of thepump chamber 39 when the piston rod 19 is moved towards the valvehousing 43 in order to commence a sawing operation, the volume of thepump chamber 39 decreasing as a result of a larger part of the centralpipe 40 being located within the pump chamber 39. When the saw bar 3 isreturned by the piston rod 19 being moved in the opposite direction, thevolume in the pump chamber 39 increases to a corresponding degree sincea smaller part of the central pipe 40 is located within the pump chamber39. Due to the partial pressure now arising in the pump chamber 39 thelubricant will be sucked into the pump chamber 39 from the lubricatingoil tank 44 via pipe 45, channel 46 with its opened non-return valve 51and the central pipe 40.

From the inlet 49 the lubricant is conveyed to the saw chain 4 viaconnections in the saw motor 6, toothed wheel 26, holder 2 and a conduit53 having its orifice close to the saw chain 4. Said connectionscomprise a circular channel formed by opposing grooves 54, 55 in theflange of the saw motor 6 and the toothed wheel 26, a channel (notshown) in the saw motor 6, which connects said inlet 49 with saidcircular channel, and radial and axial channels 56, 57 which connect thecircular channel 54 with said conduit 53 with its orifice close to thesaw chain 4.

Between them the flange of the saw motor 6 and the toothed wheel 26define a second similar circular channel in order to provide saidhydraulic piston cylinders with pressure oil via similar axial andhorizontal channels in the saw motor 6, toothed wheel 26 and holder 2from an inlet 49 in the motor cover 50. The circular channels are sealedby means of sealing rings 59 inserted in peripheral grooves.

The saw assembly also comprises a special device for sensing andrecording the angular position and, in the embodiment shown, also thedirection of movement of the saw bar 3 in relation to its home position.This device comprises a small toothed wheel 60 (see FIG. 2) which is intoothed engagement with the toothed wheel 26 of the feeding-out andfeeding-in device 14 and two sensors 61, 62 one of which, in thestarting position of the saw bar 3, is situated immediately opposite agap between two teeth, whereas the other is situated immediatelyopposite a tooth. The small toothed wheel 60 is considerably smallerthan the toothed wheel 26 of the feeding-out and feeding-in device 14 sothat a large gear ratio is obtained which, in the embodiment shown, is3.25:1. A slight rotation of the saw bar 3 thus gives a large movementon the small toothed wheel 60, which movement is sensed by the sensors61, 62 which create pulse trains which are recorded and processed by acomputer. The arrangement with two toothed wheels 26, 60 with large gearratio and sensors 61, 62 enables extremely small angular movements ofthe holder 2 to be sensed and recorded with a sensor system, i.e. anangular movement of 2°. This should be compared with known arrangementswhere only 7° can be sensed and recorded. A sensor 63 is also providedwhich senses the home position of the piston rod 19 in order to indicatethe home position of the saw bar 3. One of the two sensors 61, 62 may beomitted if information concerning the direction of movement of the sawbar is unnecessary. In certain cases it is sufficient if said gear ratiois 1.5:1 or more. It is valuable to utilize the small angular movementsto initiate marking of the sawn cut surface with a marking liquid whichmust be sprayed out at an exact moment in the sawing operation, when thebar has assumed a specific position in the first part of the saw cut.Start and stop signals for the supply of liquid are controlled by meansof electronic signals from a control device with an electronic sensorsystem comprising said sensors 61 or 62 which sense the angular positionof the bar holder 2 in relation to the stand 1, and a sensor on thegripping arms, for instance, which senses the diameter of the tree andis arranged on the saw assembly.

What is claimed is:
 1. A saw assembly for a grip-harvester, comprising:astand; a saw bar; a chain sprocket; a said saw chain running around saidbar and said chain sprocket; a bar holder pivotably journalled on saidstand; a saw motor driving said chain sprocket; a hydraulic cylindermounted on said stand and having a piston rod and a connection to saidbar holder so as to move said saw bar in and out to perform a sawingoperation; wherein said connection comprises a first toothed wheelpivotably journalled in said stand, and coaxially, rigidly joined tosaid bar holder, at least a sector of a first toothed wheel rim mountedlevel with and facing said piston rod; said piston rod including a rackwith teeth facing said first toothed wheel and in engagement with saidteeth on said at least a sector of said rim; and a device for sensingand recording angular position of said saw bar in relation to an initialposition, said sensing and recording device comprising a second toothedwheel which is smaller than and is in toothed engagement with said firsttoothed wheel so that a gear ratio of >1 is obtained, and said sensingand recording device including at least one sensor which, in saidinitial position of said saw bar, is positioned immediately opposite agap between two teeth or immediately opposite a tooth in said secondtoothed wheel.
 2. A saw assembly as claimed in claim 1 wherein the gearratio between said first and second toothed wheels is greater than1.5:1.
 3. A saw assembly as claimed in claim 1 wherein the gear ratiobetween said first and second toothed wheels is greater than 3:1.
 4. Asaw assembly as claimed in claim 1 further comprising a bearingpositioned within an axial extension of said first toothed wheel topermit turning of said bar holder.
 5. A saw assembly as claimed in claim4, wherein said bearing comprises a ball bearing with an outer bearingring formed by a radially inner part of said first toothed wheel, and aninner bearing ring joined with said saw motor to form a rigid unit fixedon said stand.
 6. A saw assembly as claimed in claim 5, wherein an innersurface of said inner bearing ring is cylindrical and forms an assemblysupport for a corresponding externally cylindrical surface of alongitudinally extending assembly shaft on said saw motor.
 7. A sawassembly as claimed in claim 4 wherein the gear ratio between said firstand second toothed wheels is greater than 1.5:1.
 8. A saw assembly asclaimed in claim 4 wherein the gear ratio between said first and secondtoothed wheels is greater than 3:1.
 9. A saw assembly as claimed inclaim 5 wherein the gear ratio between said first and second toothedwheels is greater than 3:1.
 10. A saw assembly as claimed in claim 1wherein said sensing device also senses and records direction ofmovement of said saw bar, said sensing and recording device comprisingtwo sensors one of which in said initial position of said saw bar ispositioned immediately opposite a gap between two teeth, and the otherimmediately opposite a tooth, on said second toothed wheel.
 11. A sawassembly as claimed in claim 10 wherein the gear ratio between saidfirst and second toothed wheels is greater than 1.5:1.
 12. A sawassembly as claimed in claim 10 wherein the gear ratio between saidfirst and second toothed wheels is greater than 3:1.
 13. A saw assemblyas claimed in claim 10 further comprising a bearing positioned within anaxial extension of said first toothed wheel to permit turning of saidbar holder.
 14. A saw assembly as claimed in claim 13, wherein saidbearing comprises a ball bearing with an outer bearing ring formed by aradially inner part of said first toothed wheel, and an inner bearingring joined with said saw motor to form a rigid unit fixed on saidstand.
 15. A saw assembly as claimed in claim 14, wherein an innersurface of said inner bearing ring is cylindrical and forms an assemblysupport for a corresponding externally cylindrical surface of alongitudinally extending assembly shaft on said saw motor.
 16. A sawassembly as claimed in claim 1 further comprising: a lubricating oilpump built into said hydraulic cylinder to form an integrated unittherewith; said lubricating oil pump comprising a central,longitudinally extending pump chamber inside said piston rod rack; acentral pipe extending through said hydraulic cylinder and into saidpump chamber so that one end thereof is always situated in said pump;wherein said pump chamber and pressure chambers of said hydrauliccylinder are separated from each other by a plurality of sealingelements; and wherein said pump chamber communicates with a conduit viasaid central pipe so that a connection to said saw motor, first toothedwheel, and bar holder are provided in order to supply lubricating oil tosaid saw chain when volume in said pump chamber decreases.
 17. A sawassembly as claimed in claim 16 wherein the gear ratio between saidfirst and second toothed wheels is greater than 3:1.
 18. A saw assemblyas claimed in claim 16 further comprising a bearing positioned within anaxial extension of said first toothed wheel to permit turning of saidbar holder.